Alert archive / Iowa / Tornado Warnings in 2017

Tornado Warning 10, NWS Sioux Falls, SD

May 17, 2017Lyon County, Iowa

NWS Sioux Falls, SD issued this tornado warning at May 17, 2017, 3:01 PM CDT for Lyon County, Iowa. It was in force for 29 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
May 17, 2017, 3:01 PM CDT (20:01 UTC)
Expired
May 17, 2017, 3:30 PM CDT
In force
29 min
Issued by
NWS Sioux Falls, SD
Area
Storm-based polygon
Tornado
Radar indicated
Hail
1.0 in

County Lyon County, IA

The radar

The Sioux Falls radar (KFSD), 62 km from the middle of the area, began a volume at 20:02 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
May 17, 12:08 PM CDTTornado WatchSPC7 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 8.0 hours before the alert went out and 228 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Omaha, NE at 12:00Z on 2017-05-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 121 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Omaha, NE at 12:00Z on 2017-05-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 119 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
121 J/kg
Mixed-layer CIN
-156 J/kg
Mixed-layer LCL
1106 m above ground
0-6 km bulk shear
41 kt
0-1 km storm-relative helicity
119 m²/s²
0-3 km storm-relative helicity
132 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

184 
WFUS53 KFSD 172001
TORFSD
IAC119-172030-
/O.NEW.KFSD.TO.W.0010.170517T2001Z-170517T2030Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Sioux Falls SD
301 PM CDT WED MAY 17 2017

The National Weather Service in Sioux Falls has issued a

* Tornado Warning for...
  Eastern Lyon County in northwestern Iowa...

* Until 330 PM CDT
    
* At 301 PM CDT, a severe thunderstorm capable of producing a tornado
  was located near Matlock, or 10 miles northwest of Sheldon, moving
  north at 25 mph.

  HAZARD...Tornado and quarter size hail. 

  SOURCE...Radar indicated rotation. 

  IMPACT...Flying debris will be dangerous to those caught without 
           shelter. Mobile homes will be damaged or destroyed. 
           Damage to roofs, windows, and vehicles will occur.  Tree 
           damage is likely. 

* This dangerous storm will be near...
  George around 310 PM CDT. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 4326 9610 4349 9615 4350 9595 4326 9588
TIME...MOT...LOC 2001Z 167DEG 22KT 4327 9601 

TORNADO...RADAR INDICATED
HAIL...1.00IN

$$

Ferguson
2 follow-up statements
155 
WWUS53 KFSD 172018
SVSFSD

Severe Weather Statement
National Weather Service Sioux Falls SD
318 PM CDT WED MAY 17 2017

IAC119-172030-
/O.CON.KFSD.TO.W.0010.000000T0000Z-170517T2030Z/
Lyon IA-
318 PM CDT WED MAY 17 2017

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 330 PM CDT FOR EASTERN
LYON COUNTY...
    
At 317 PM CDT, a severe thunderstorm capable of producing a tornado
was located over George, or 10 miles southeast of Rock Rapids, moving
north at 20 mph.

HAZARD...Tornado. 

SOURCE...Radar indicated rotation. 

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely. 

This tornadic thunderstorm will remain over mainly rural areas of
eastern Lyon County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 4326 9610 4349 9615 4350 9595 4326 9588
TIME...MOT...LOC 2017Z 168DEG 16KT 4335 9599 

TORNADO...RADAR INDICATED
HAIL...<.75IN

$$

Ferguson
447 
WWUS53 KFSD 172024
SVSFSD

Severe Weather Statement
National Weather Service Sioux Falls SD
324 PM CDT WED MAY 17 2017

IAC119-172032-
/O.EXP.KFSD.TO.W.0010.000000T0000Z-170517T2030Z/
Lyon IA-
324 PM CDT WED MAY 17 2017

...THE TORNADO WARNING FOR EASTERN LYON COUNTY WILL EXPIRE AT 330 PM
CDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer appears capable of producing a tornado.
Therefore the warning will be allowed to expire.  However heavy rain
is still possible with this thunderstorm.

A tornado watch remains in effect until 700 PM CDT for northwestern
Iowa.

LAT...LON 4326 9610 4349 9615 4350 9595 4326 9588
TIME...MOT...LOC 2022Z 167DEG 22KT 4338 9600 

$$

Ferguson

The office that day

Everything else NWS Sioux Falls, SD issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 16, 7:43 PM CDTSevere Thunderstorm WarningFSDIda33 min
May 16, 8:22 PM CDTSevere Thunderstorm WarningFSDBuena Vista23 min
May 17, 11:16 AM CDTRiver Flood WarningFSDClay24 hr
May 17, 11:16 AM CDTRiver Flood WarningFSDBuena Vista, Clay24 hr
May 17, 11:16 AM CDTRiver Flood WarningFSDPlymouth, Sioux5 days
May 17, 11:16 AM CDTRiver Flood WarningFSDPlymouth6 days
May 17, 11:16 AM CDTRiver Flood WarningFSDClay4 days
May 17, 11:16 AM CDTRiver Flood WarningFSDClay, Dickinson59 hr
May 17, 1:33 PM CDTTornado WarningFSDSioux27 min
May 17, 1:56 PM CDTTornado WarningFSDSioux34 min
May 17, 2:03 PM CDTTornado WarningFSDSioux27 min
May 17, 2:28 PM CDTTornado WarningFSDLyon, Sioux32 min
May 17, 2:34 PM CDTSevere Thunderstorm WarningFSDLyon26 min

Nearby

Tornado Warnings in Iowa, 2017Every tornado warning in 2017Tornadoes in 2017

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.